Electric discharge tube



June 2, 1942. F. HERRIGER 2,234,555

ELECTRIC DISCHARGETUBE Filed Sept. 24, 1940 Patented` June 2, 1942 lELECTRIC DISCHARGE TUBE Felix Herrger, Berlin, Germany, assignor to C.Lorenz Aktiengesellschaft, Berlin-Tempelhof, Germany, a companyApplication September 24, 1940, Serial No. 358,068

In Germany October 26, 1939 1 Claim.

This invention is concerned with flat cathodes of the kind employed inelectron tubes. More particularly the invention relates to cathodeswhich comprise a ilat carrier body and an emissive layer fitted to it ononly one side thereof, namely, the side on which the other electrodes,as anode and grid, are located.

In the copending application of E. Lpp et al., Serial No. 289,644, filedAugust 11, 1939, a cathode is described which on the other or oppositeside of the flat carrier body, that is, the side having no emissivelayer, is covered with a protective layer in order to prevent thecarrier body, made of nickel, for instance, from volatilizing orevaporating on this side during the operation of the tube. According tothis copending application such protective layer may consist of analkaline earth oxide or may be a ceramic disc.

According to the invention described hereafter it is proposed that aradiation inhibiting layer be arranged to constitute the protectivelayer, as will be understood from the following description. 'I'heaccompanying drawing shows a diagrammatic sectional view of an electrontube Whose cathode is an example of devices as provided by theinvention.

In a vacuum vessel I an anode 2, a grid 3 and a cathode are contained.The cathode comprises a ilat metallic carrier body 4, an emissive layer5 arranged to face the grid, and a. radiation inhibiting layer 8 on theside remote from the grid. Layer 8 comprises a highly polished metalwhich has an optical radiating capacity less than that of the carrierbody 4. As a result this body is prevented from volatilizing, wherebythe heating power to be supplied to it is considerably less than inprior devices.

What is claimed is:

A discharge tube having a cathode which comprises a flat metalliccarrier body, an emissive layer fitted to this body on one side thereof,and a radiation inhibiting layer tted to the carrier body on the otherside, said radiation-inhibiting layer comprising a highly polished metalhaving an -optical radiating capacity less than that of the carrierbody.

FELIX HERRIGER.

